Research On The Resistance Of FRP Reinforced RC Frame Structure To Continuous Collapse

Reinforced concrete frame structure under accidental load, if the local component damage occurs, the entire structure is prone to continuous collapse, which cause great casualties and property losses. This article in view of some problems of the existing continuous collapse resistance reinforcement measures, such as reinforcement effect is limited, design and construction is difficult, effect the beauty of the structure, etc. This article suggest a new type of continuous collapse resistance reinforcement measures, layout of FRP bar in the interior of the frame beam to improve the continuous collapse resistance of the beam. In this paper, the main research contents and conclusions are as follows:(a) Evaluate the continuous collapse resistance of a five floors reinforced concrete frame by SAP2000 software. The results show that, the continuous collapse resistance of the structure which is not reinforcement is obviously insufficient.(b) Analysis the continuous collapse resistance of the reinforced concrete frame, which has been strengthened with FRP bar, by AP method. The results show the new type of reinforcement measures can effectively enhance the continuous collapse resistance of the structure. The not collapsed percentage of the reinforced structure reinforcement structure is 100%. According to the results of the analysis, put forward the four stages of change for the failure vertical pillars speed-time curve:speed exploding stage, speed shock stage, speed slowly decrease, speed violently increase stage.(c) Study the influence of reinforcement ratio of FRP bar to reinforcement effect. The results show that, the demand of FRP bar reinforcement ratio from big to small is following:long edge of the column, corner column, internal column, short edge of column structure. The effect of reinforcement effect by the change of reinforcement ratio on the short edge of the column and internal column is smaller. When the frame beam span less than 4.2 m, the reasonable reinforcement ratio of the FRP bar is not more than 0.3%. When the frame beam span from 4.2 m to 4.8 m, the reasonable reinforcement ratio is 0.4%～0.6%.(d) Study the impact of three kinds of reinforcement, all-layer reinforcement, isolation-layer reinforcement, single-layer reinforcement, on the FRP reinforcement effect. The results show that, the strengthening effect of different reinforcement method from good to bad is following:all-layer reinforcement, isolation-layer reinforcement, single-layer reinforcement. Respectively, the percentage of structure collapse is 15%,60% and 75%.The most significant reinforcement method is all-layer reinforcement. The time of structure collapse is greater than 5.0 s on this reinforcement method.(e) Study the influence of seismic fortification level on FRP reinforcement effect. The results show that, FRP reinforcement effect is proportional to the structural seismic fortification levels. The higher of fortification level, the FRP reinforcement effect is more significant. Respectively, the percentage of the reinforced structure collapse, under 6°, 7°,8°seismic intensity condition, is 70%,100% and 100%.(f) Study the influence of frame column spacing of FRP reinforcement effect. The results show that, the demand of FRP bar is proportional to the frame column spacing. When the strength of FRP bar is same, the collapse time of structure as the column spacing increases gradually in advance. When the frame column spacing below than 4.2m, the demand of FRP bar is relatively low. When the frame column spacing greater than 5.4m, the demand of FRP bar is significantly increase. In order to improve the efffect of FRP bar, it is suggested that the reasonable frame column spacing from 4.2m to 5.4m.